Difference Between 2 Way and 3 Way Light Switch

difference between 2 way and 3 way light switch


Nowadays people are widely using the three way switches. However, the usage of two switches isn’t decreasing too. 

Just from the name, we can assume that these switches are different. And that’s true Both these switches have different working principles. 

We’re assuming that you are up to buying new switches. And we’re guessing that you’re in a dilemma about choosing between these two options. 

To help you out we have crafted out this piece. Here we have discussed the difference between 2 way and 3 way light switch. 

That’s not all-

We have divided the discussion in two parts. In first part, we have a feature specific difference table. On the second, we have a working principle based discussion. 

So, let’s get going without wasting any more time-

2 Way vs 3 Way Switch

Before jumping straight into the feature specific table, let’s go through some useful information. So, what is a 2 way switch?

The 2 way switch or single pole double throw switch is a three terminal switch. Here 1 terminal is the input and the other two are used as outputs. It’s okay if this is too complex for you. We’ll break it down pretty soon. Now, let’s look at the 3 way switch. 

So, why is it called a 3 way switch

Because it uses two switches and one appliance. In 3 way switches you use two control a single appliance from two different locations. 

Now let’s look at the feature specific differences-

2 Way Switch

3 Way Switch

These have on/off switches

Do not have an on/off switch

These switches don’t have hot wires.

These switches have hot wires

These switches have 3 terminals

These switches actually have 4 terminals

These switches use only 2 types of wires. 

These switches use 3 types of wires. 

Installing 2 way switches are easy.

Installing 3 way switches are more complex. 

Working Principles of 2 way and 3 Way Switches

Here we will try to explain how these switches work in the simplest possible way. But we always recommend you watching real live video tutorials about these. 

So, let’s go through the switches one by one-

How 2 way Switch Works?

Let’s assume that 2 switches S1 and S2 are controlling a bulb. Now we have two types of wires coming to the switches. The neutral and the hot wire. 

Each of the switches have 3 terminals. One is common and the other two are output. In 2 way switching, the live wire connects with the common terminal of S1. On the other hand, another hot wire connects the S2 common terminal and the bulb. 

The remaining output terminals are connected with each other through two sets of wires. 

The neutral wire goes directly to the bulb. 

Now let’s name the output terminals as S1L1, S1L2, S2L1, and S2L2. It’s better if you draw a diagram at this point. 

The terminals are named like this; Switch name – Terminal Number. So, S2L1 means the 1st terminal of Switch 2. 

Now, if the switch terminal are disconnected in any combination, then the bulb will remain off. If the circuit gets completed, then we’ll see a lit bulb. 

How does three way switch work?

The three way switch comes with three terminal screws and one ground wire screw. In total it has 4 terminal screws. 

There’s a dark colored terminal named ‘COM’ in 3 way switches. The remaining two terminals are called as interchangeable and travelers. 

You’ll typically find the traveler wires with black and red insulation. Once the switches are installed, these wires come do the main action. These wires pass or interrupt electrical current between the switches. 

When the connected appliance or light fixture is on, the current goes through any of those black or red travelers. 

Final Thoughts

We’re at the end our journey. We believe that now you can give out lecture on these switch types. However, don’t go on working on these switches if you’re not sure about some details. 

Working with electricity is extremely dangerous. 

However, if you’re thinking about installing light switches, then we would recommend 3 way switches. Because these are super safe. 

Good luck and don’t forget to ask us about anything that seemed confusing to you. 

Alex Dantas

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